Spark plug terminal



United States Patent 2,736,877 SPARK PLUG TERMINAL Wilfred A. Bychinsky,Ann Arbor, Mich. assignor to General Motors Corporation, Detroit, Micln,a corporation of Delaware Application October 10, 1951, Serial No.250,757 6 Claims. (c1. 339-L258) This invention relates to spark plugsand in particular to improvements in spark plug terminals whereby toaccommodate a single spark plug to a plurality of different installationrequirements.

In the prior art it has been customary and considered necessary toprovide spark plugs of special configuration to accommodate them to theparticular installation requirements encountered in various engines. Asan example, spark plugs of identical design are ofttimes made in severaldifferent lengths to accommodate them to particular engine block andspark plug well configurations. This situation not only has necessitatedthe manufacture of spark plugs of the same technical specification andof several different lengths but causes the many thousands of automobiledealers, motor boat dealers, distributors, garages and service stationsthroughout the United States and foreign countries to carry in stockmany more types of spark plugs than would be required otherwise.

With the foregoing in view, it is an object of this invention to providespark plugs with terminals that accommodate the spark plugs to more thana single installation requirement.

Another object of the invention is to provide, in a spark plug, terminalconstruction formed to receive a cable terminal at the end of the sparkplug terminal or optionally at a point short of the end of the sparkplug terminal.

A further object of the invention is to provide a unitary spark plughaving a relatively long terminal formed into two or more cable terminalreceiving elements having a frangible section therebetween whereby topermit the upper portion of the spark plug terminal to be broken offthereby producing a spark plug having a relatively shorter terminal.

Other objects of the invention will become apparent by reference to thefollowing detailed description taken in connection with the accompanyingdrawing, in which:

Fig. 1 is a vertical sectional view of a relatively long terminal sparkplug of the type having a two piece terminal comprising a terminal pinand a long terminal head in the form of a nut threaded on the terminalpin, the invention being incorporated in the long terminal nut or head.

Fig. 2 is an enlarged fragmentary vertical sectional view similar toFig. 1 showing a portion of the long terminal nut or head broken offproviding a relatively short terminal spark plug.

Fig. 3 is an enlarged fragmentary sectional view of the long terminalnut or head shown in Fig. 1.

Fig. 4 is a vertical sectional view of a relatively long terminal sparkplug having a one piece terminal including a long terminal head, theinvention being incorporated in the long terminal head.

Fig. 5 is an enlarged fragmentary sectional view similar to Fig. 4showing a portion of the long terminal head broken off providing arelatively short terminal spark plug.

Fig. 6 is an enlarged fragmentary sectional view of the long terminalhead shown in Fig. 4.

2,736,877 Patented Feb. 28, 1956 Referring now to the drawing whereinlike reference characters refer to like and corresponding partsthroughout the several views, the illustrative embodiment of theinvention'disclosed in Figs. l-3 inclusive is shown in connection with aspark plug 10 having 'a two piece terminal composed of a relatively longterminal nut or head 11 threaded onto the extending threaded end of theterminal pin 12, the said terminal pin 12 being threaded or otherwiseupset at its lower end and secured by sealing material 13 within theterminal pin well of the insulator element 14 against the top of thecentral electrode 15. A gasket16 is preferably employed between theterminal nut or 'head 11 and the topv of the insulator element 14 toprevent moisture or foreign matter from accumulating in the terminal pmwell 140 of the insulator element 14. I

v The terminal nut or head 11 is provided with an axial bore 17therethrough and is interiorly threaded at its lower end at 170. Theupper end of the terminal head 11 is exteriorly contoured in a suitablemanner at A and B to receive and retain a snap-on type cable terminalpositionedover the upper end thereof. Between the contoured portions Aand B, the terminal head 11 is made frangible by such means as cutting acircumferential Weakening groove 18 therearound whereby to permit theupper contoured portionA of the terminal head 11 to be broken neatlyaway therefrom as indicated by the dot anddash lines in Fig. 3 leavingthe lower contoured portion B ready to receive and retain a snap-on typecable terminal. Thus, a spark plug having either a long or a shortterminal is provided. Qbviously, more than two snap-on type cableterminal contours may be formed on the terminal head or nut 11 withweakened sections therebetweento provide in a single spark plug morethan two terminal lengths.

Although the weakening deformation may be of any suitable configuration,it is preferable that, if a circumferential groove 18 is employed, thedeepest portion thereof be located adjacent the annular shoulder 19below the groove to assure that the break at the top of the contour Bwill be accurate and relatively smooth. The circumferential weakeninggroove 18 is preferably located above the threaded end 120 of theterminal pin 12 to permit the contoured portion A to be easily brokenoff the terminal nut or head 11 without removing it from the terminalpin 12.

The embodiment of the invention shown in Figs. 46 inclusive is like andsimilar to the embodiment of the invention shown in Figs. l-3 inclusiveexcept that the relatively long terminal head 21 of the spark plug 20and the terminal pin 22 are integral, and the top of the long terminalhead 21 is axially bored at 23 to a point below the circumferentialweakening groove 18 located between the exteriorly contoured portions Aand B of the terminal head 21.

Although but two embodiments and applications of the invention have beenshown in the drawing and described in detail, it is obvious thatmany'changes may be made in the size, shape, arrangement and detail ofthe elements of the invention without departing from the spirit andscope thereof as defined by the appended claims.

I claim:

1. In a spark plug, a terminal including a relatively long head havingan upper contoured portion to receive a cable terminal at the endthereof and a lower contoured portion to receive a cable terminal shortof the end thereof, said head having a circumferential groovetherearound between said contoured portions deeper adjacent the lowercontoured portion than adjacent the upper contoured portion weakeningthe said terminal therebetween to permit breaking off the uppercontoured portion accurately to provide a relatively shorter terminalspark plug.

2. A spark plug including a terminal therefor, a head on said terminalhaving a contoured portion at the end thereof and another contouredportion short of the end thereof, said contoured portions being ofsubstantially identical shape and each being adapted to receive a cableterminal, said head having a frangible section between said contouredportions to permit shortening the spark plug terminal by breaking theterminal head between the contoured portions thereof.

3. In a spark plug, a terminal including a relatively long head having acontoured portion to receive a cable terminal at the end thereof and asecond contoured portion to receive a cable terminal short of the endthereof, said contoured portions being of substantially identical shape,said head having a circumferential groove therearound between saidcontoured portions weakening the said head therebetween to permitbreaking off the end contoured portion to provide a relatively shorterterminal spark plug.

4. A spark plug including a threaded terminal pin extending therefrom, ahollow relatively long terminal nut threaded at its lower end on saidterminal pin, said terminal nut having an upper contoured portion toreceive a cable terminal at the end thereof and a lower contouredportion short of the end thereof, said contoured portions being ofsubstantially identical shape, and said terminal nut having acircumferential weakening groove therearound between said contouredportions, said upper contoured portion and weakening groove beinglocated above the terminal pin to permit the upper contoured portion tobe readily broken away to provide optionally a relatively short terminalspark plug.

5. A spark plug including a terminal therefor, a head on said terminalhaving an upper contoured portion at the end thereof and a lowercontoured portion short of the end thereof, said contoured portionsbeing of substantially identical shape and each being adapted to receivea cable terminal, said head having a circumferential groove therearoundbetween said contoured portions deeper adjacent the lower contouredportion than adjacent the upper contoured portion weakening the saidhead therebetween to permit breaking off the upper contoured portionaccurately to provide a relatively shorter terminal spark plug.

6. A spark plug including a threaded terminal pin extending therefrom, ahollow relatively long terminal nut threaded at its lower end on saidterminal pin, said terminal nut having an upper contoured portion toreceive a cable terminal at the upper end thereof and a lower contouredportion to receive a cable terminal short of the upper end thereof, saidcontoured portions being of substantially identical shape, and saidterminal nut having a circumferential groove therearound between saidcontoured portions deeper adjacent the lower contoured portion thanadjacent the upper contoured portion, said upper contoured portion andgroove being located above the terminal pin to permit the uppercontoured portion to be accurately broken away to provide optionally arelatively short terminal spark plug.

References Cited in the file of this patent UNITED STATES PATENTS Re.19,092 Despard Feb. 20, 1934 962,621 Carlson June 28, 1910 1,297,560Groenenstein Mar. 18, 1919 1,580,562 Moore Apr. 13, 1926 1,677,269Burghart July 17, 1928 1,696,523 Cochran Dec. 25, 1928 1,952,554Lavarack Mar. 27, 1934 1,960,309 Herron May 29, 1934 2,085,074 BoylesJune 29, 1937 2,212,145 Benander Aug. 20, 1940

